signal.hpp File Reference

Signal<T>, Computed<T> and Effect: the nodes of a reactive graph. More...

#include <concepts>
#include <cstddef>
#include <cstdint>
#include <exception>
#include <functional>
#include <memory>
#include <optional>
#include <stdexcept>
#include <type_traits>
#include <utility>
#include "detail/graph.hpp"
#include "runtime.hpp"

Go to the source code of this file.

Classes
class	morph::reactive::Signal< T >
	A source value. Reading it with get() inside a tracked run subscribes that run. More...
class	morph::reactive::Computed< T >
	A derived value: computed lazily on first read, cached, and recomputed only after a source it read really changed. More...
class	morph::reactive::Effect
	A side effect: runs once on construction, then in a flush after any source it read changed. More...

Enumerations
enum class	morph::reactive::EqualityPolicy : std::uint8_t { Auto , Always }
	Whether a Signal or Computed compares a new value with the current one before notifying. More...

Variables
template<typename T>
constexpr bool	morph::reactive::kEqualityUsable = detail::EqualityUsable<std::remove_cv_t<T>>::value
	Whether == is usable for T, which is what the EqualityPolicy::Auto skip needs.

Detailed Description

Signal<T>, Computed<T> and Effect: the nodes of a reactive graph.

Specified in docs/spec/reactive/signals.md.

Definition in file signal.hpp.

Enumeration Type Documentation

EqualityPolicy

enum class morph::reactive::EqualityPolicy : std::uint8_t

strong

Whether a Signal or Computed compares a new value with the current one before notifying.

Enumerator
Auto	Skip a value equal to the current one, when == is usable for the type (kEqualityUsable).
Always	Notify on every write or recomputation, even of an equal value.

Definition at line 26 of file signal.hpp.

Variable Documentation

kEqualityUsable

template<typename T>

bool morph::reactive::kEqualityUsable = detail::EqualityUsable<std::remove_cv_t<T>>::value

inlineconstexpr

Whether == is usable for T, which is what the EqualityPolicy::Auto skip needs.

Checked through element types, not by std::equality_comparable alone: a standard container declares == for any element type, and comparing two of them fails to compile when the element has none. A type for which this is false always notifies.

Template Parameters

T	The value type.

Definition at line 40 of file signal.hpp.